Yamaha YZ450F(D) Owner's Service Manual page 219

FUEL PUMP SYSTEM
INSPECTION STEPS
If the fuel pump is not operating normally, perform the following procedures in the order given.
Check engine stop switch.
OK ↓
Checking the couplers and leads connections
OK ↓
Check the fuel pump.(Checking the fuel pump
body)
OK ↓
Replace the ECU.
• Remove the following parts before inspection.
1. Seat
2. Side cover (right/left)
3. Fuel tank
• Use the following special tools in this inspection.
Pocket tester:
YU-03112-C/90890-03112
Test harness S-pressure sensor (3P):
YU-03207/90890-03207
No good → Replace.
No good → Repair or replace.
No good →
Replace the fuel pump assembly.
7-35
FUEL PUMP SYSTEM